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A Stable Nitrogen‐centered Bis(imino)perylene Dimer‐based Diradicaloid
Author(s) -
Xiao Zhanhui,
Zeng Jian,
Phan Hoa,
Herng Tun Seng,
Gopalakrishna Tullimilli Y.,
Ding Jun,
Zeng Wangdong,
Wu Jishan
Publication year - 2020
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.202000285
Subject(s) - diradical , chemistry , perylene , steric effects , radical , photochemistry , singlet state , dimer , heteroatom , delocalized electron , paramagnetism , crystallography , excited state , stereochemistry , molecule , organic chemistry , ring (chemistry) , atomic physics , physics , quantum mechanics
Carbon‐centered radicals are usually reactive and there are only few stable heteroatom‐centered organic radicals. Herein, we report a nitrogen‐centered bis(imino)perylene dimer based diradicaloid 2Per‐2 N , which has a large diradical character ( y 0 =72%) but still shows reasonable stability due to kinetic blocking of the aminyl radical sites by the bulky and electron‐deficient 2,4,6‐trichlorophenyl groups and effective spin delocalization. It displays thermally populated paramagnetic activity with a moderate singlet‐triplet energy gap (Δ E S–T =−3.55 kcal/mol). Compared with a fully fused bis(imino)quaterrylene analogue ( QR‐2 N ) which is a typical closed‐shell compound, 2Per‐2 N possesses a much larger diradical character mainly due to the steric repulsion between the neighboring perylene units in the rigid quinoidal form. 2Per‐2 N exhibits a much smaller energy gap and longer absorption wavelength compared with QR‐2 N. 2Per‐2 N represents a rare example of stable nitrogen‐centered diradicaloid with a large diradical character.